Heat transfer correlations for air-water two-phase flow of different flow patterns in a horizontal pipe

2001 ◽  
Vol 15 (12) ◽  
pp. 1711-1727 ◽  
Author(s):  
Dongwoo Kim
Keyword(s):  
Heat Transfer ◽  
Two Phase Flow ◽  
Flow Patterns ◽  
Phase Flow ◽  
Two Phase ◽  
Horizontal Pipe ◽  
Heat Transfer Correlations

Two-Phase Flow and Heat Transfer in Rectangular Micro-Channels

2003 ◽  
Author(s):  
Weilin Qu ◽  
Seok-Mann Yoon ◽  
Issam Mudawar
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Flow Pattern ◽  
Two Phase Flow ◽  
Flow Patterns ◽  
Heat Sinks ◽  
Phase Flow ◽  
Micro Channel ◽  
Two Phase ◽  
Micro Channels

Knowledge of flow pattern and flow pattern transitions is essential to the development of reliable predictive tools for pressure drop and heat transfer in two-phase micro-channel heat sinks. In the present study, experiments were conducted with adiabatic nitrogen-water two-phase flow in a rectangular micro-channel having a 0.406 × 2.032 mm cross-section. Superficial velocities of nitrogen and water ranged from 0.08 to 81.92 m/s and 0.04 to 10.24 m/s, respectively. Flow patterns were first identified using high-speed video imaging, and still photos were then taken for representative patterns. Results reveal that the dominant flow patterns are slug and annular, with bubbly flow occurring only occasionally; stratified and churn flow were never observed. A flow pattern map was constructed and compared with previous maps and predictions of flow pattern transition models. Annual flow is identified as the dominant flow pattern for conditions relevant to two-phase micro-channel heat sinks, and forms the basis for development of a theoretical model for both pressure drop and heat transfer in micro-channels. Features unique to two-phase micro-channel flow, such as laminar liquid and gas flows, smooth liquid-gas interface, and strong entrainment and deposition effects are incorporated into the model. The model shows good agreement with experimental data for water-cooled heat sinks.

Heat Transfer Correlations for Air-Water Two-Phase Flow of Different Flow Patterns in a Horizontal Pipe

2000 ◽  
Author(s):  
Dongwoo Kim ◽  
Jae-yong Kim ◽  
Afshin J. Ghajar ◽  
Ronald L. Dougherty
Keyword(s):  
Heat Transfer ◽  
Flow Patterns ◽  
Mean Deviation ◽  
Water Mixture ◽  
Two Phase ◽  
Horizontal Pipe ◽  
Flux Boundary Condition ◽  
Uniform Wall ◽  
Heat Transfer Correlations ◽  
Two Phase Heat Transfer

Abstract New heat transfer correlations were developed for two-phase heat transfer in a horizontal pipe for different flow patterns. Flow patterns were observed in a transparent circular pipe (2.54 cm I.D. and L/D = 96) using an air/water mixture. Visual identification of the flow patterns was supplemented with photographic data, and the results were plotted on the flow regime map proposed by Taitel and Dukler and agreed quite well with each other. A two-phase heat transfer experimental setup was built for this study and a total of 150 two-phase heat transfer data with different flow patterns were obtained under a uniform wall heat flux boundary condition. For these data, the superficial Reynolds number ranged from 640 to 35,500 for the liquid and from 540 to 21,200 for the gas. Our previously developed robust two-phase heat transfer correlation for a vertical with modified constants predicted the horizontal pipe air-water heat transfer experimental data with good accuracy. Overall the proposed correlations predicted the data with a mean deviation of 1.0% and an rms deviation of 12%.

Two-Phase Flow and Heat Transfer in Rectangular Micro-Channels

2004 ◽  
Vol 126 (3) ◽  
pp. 288-300 ◽  
Author(s):  
Weilin Qu ◽  
Seok-Mann Yoon ◽  
Issam Mudawar
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Flow Pattern ◽  
Two Phase Flow ◽  
Flow Boiling ◽  
Flow Patterns ◽  
Heat Sinks ◽  
Phase Flow ◽  
Micro Channel ◽  
Two Phase

Knowledge of flow pattern and flow pattern transitions is essential to the development of reliable predictive tools for pressure drop and heat transfer in two-phase micro-channel heat sinks. In the present study, experiments were conducted with adiabatic nitrogen-water two-phase flow in a rectangular micro-channel having a 0.406×2.032mm2 cross-section. Superficial velocities of nitrogen and water ranged from 0.08 to 81.92 m/s and 0.04 to 10.24 m/s, respectively. Flow patterns were first identified using high-speed video imaging, and still photos were then taken for representative patterns. Results reveal the dominant flow patterns are slug and annular, with bubbly flow occurring only occasionally; stratified and churn flow were never observed. A flow pattern map was constructed and compared with previous maps and predictions of flow pattern transition models. Features unique to two-phase micro-channel flow were identified and employed to validate key assumptions of an annular flow boiling model that was previously developed to predict pressure drop and heat transfer in two-phase micro-channel heat sinks. This earlier model was modified based on new findings from the adiabatic two-phase flow study. The modified model shows good agreement with experimental data for water-cooled heat sinks.

Two phase flow heat transfer analysis at different flow patterns in the wellbore

2017 ◽  
Vol 117 ◽  
pp. 544-552 ◽  
Author(s):  
Yonghai Gao ◽  
Yanchun Cui ◽  
Boyue Xu ◽  
Baojiang Sun ◽  
Xinxin Zhao ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Two Phase Flow ◽  
Flow Patterns ◽  
Heat Transfer Analysis ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Heat

Distinguish the Pattern of Two-Phase Flow with the Technology of Acoustic Emission

2013 ◽  
Vol 816-817 ◽  
pp. 502-505
Author(s):  
Li De Fang ◽  
Yao Zhang ◽  
Wan Ling Zhang ◽  
Qing He ◽  
Yu Jiao Liang
Keyword(s):  
Acoustic Emission ◽  
Two Phase Flow ◽  
New Technology ◽  
Bubbly Flow ◽  
Flow Patterns ◽  
New Method ◽  
Good Effect ◽  
Phase Flow ◽  
Two Phase ◽  
Horizontal Pipe

This paper has propose a new method (acoustic emission) to distinguish the pattern of gas-liquid two-phase flow in the horizontal pipe. The signals which got from the probe when multiphase flow pattern changes in the pipe and the four probe installed on the different position. Through the analysis of time domination, energy of wavelet, collected the signal features and shows there has a significant differences among the three typical flow patterns (bubbly flow, stratified flow, annular flow). Energy of wavelet can clearly represents the signal strength. This paper found that the acoustic emission as a new method to distinguish flow patterns have good effect can as a new technology for the study of gas-liquid two-phase.

Two-Phase Flow Patterns During Microchannel Vaporization of CO2 at Near-Critical Pressures

2003 ◽  
Author(s):  
Jostein Pettersen
Keyword(s):  
Heat Transfer ◽  
Flow Pattern ◽  
Mass Flux ◽  
Two Phase Flow ◽  
Bubble Formation ◽  
Glass Tube ◽  
Flow Patterns ◽  
High Mass ◽  
Phase Flow ◽  
Two Phase

Carbon dioxide (CO2 / R-744) is receiving renewed interest as a refrigerant, in many cases based on systems with microchannel heat exchangers that have high pressure capability, efficient heat transfer, and compact design. A good understanding of two-phase flow of evaporating CO2 in microchannels is needed to analyze and predict heat transfer. A special test rig was built in order to observe two-phase flow patterns, using a horizontal quartz glass tube with ID 0.98 mm, externally coated by a transparent resistive film. Heat flux was obtained by applying DC power to the film, and flow patterns were recorded at 4000 or 8000 frames per second by a digital video camera. Flow patterns were recorded for temperatures 20°C and 0°C, and for mass flux ranging from 100 to 580 kgm−2s−1. The observations showed a dominance of intermittent (slug) flow at low x, and wavy annular flow with entrainment of droplets at higher x. At high mass flux, the annular/entrained flow pattern could be described as dispersed. The aggravated dryout problem reported from heat transfer experiments at high mass flux could be explained by increased entrainment. Stratified flow was not observed in the tests with heat load. Bubble formation and growth could be observed in the liquid film, and the presence of bubbles gave differences in flow pattern compared to adiabatic flow. The flow pattern observations did not fit generalized maps or transition lines showed in the literature.

Two- phase flow patterns and heat transfer in parallel microchannels

2002 ◽  
Vol 11 (4) ◽  
pp. 353-358 ◽  
Author(s):  
A. Mosyak ◽  
Z. Segal ◽  
E. Pogrebnyak ◽  
G. Hetsroni
Keyword(s):  
Heat Transfer ◽  
Two Phase Flow ◽  
Flow Patterns ◽  
Phase Flow ◽  
Two Phase ◽  
Parallel Microchannels
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